Jamie Carragher doesn't feel Victor Lindelof "should be playing at this level" after Manchester United's defensive problems worsened on Monday night against Tottenham.
Two goals from Lucas Moura and another from Harry Kane condemned United to a second consecutive defeat in eight days following the disappointing reverse at Brighton last Sunday.
United's defence was again at fault - as it was at the Amex - with individual errors costing the home side dear at Old Trafford and heaping yet more pressure on manager Jose Mourinho.
Lindelof, a £31m signing from Benfica last summer, came on in the second half in place of an injured Phil Jones with Carragher left particularly unimpressed with what he saw from the Swedish international.
"I actually feel a bit sorry for him [Lindelof], he should not be playing at this level," he said on Sky Sports Monday Night Football.
"Phil Jones and Chris Smalling have been playing for a long time, and it [the mistakes] shouldn't be happening at this level."
He added: "There's a serious lack of quality, if you've spent £400m on a squad. How do you lose 3-0? That's a team that looks like it still needs £200m spent on it.'
Meanwhile former United defender Gary Neville says Jose Mourinho must now face up to "the biggest challenge he has had in football".
There was a mixed reception on the final whistle from the Old Trafford crowd as United followed up defeat at Brighton with another loss, prompting questions over the future of the former Chelsea manager and Neville admitted he has a huge job on his hands if he is to try and reverse the club's fortunes.
"The manager is always the person where the buck stops," he added. "Jose Mourinho has been the most successful manager along with Pep Guardiola in the last 20 years in football and he is going through a difficult moment now over the last couple of seasons with Manchester United.
"This is now the biggest task he has had in his life and the biggest challenge he has had in football.
"He has got to come out of it because I have to say I look at the squad and the team and I'm not sure what the best XI is.
"He is going to have to back certain players and just stick with it because at the moment they are changing every game.
"The buck stops with the manager, it always does and it has to. At the moment there doesn't look to be a balanced outfit there at all."
